Cisco Cisco Email Security Appliance C160 Mode D'Emploi

Host DNS verification settings for sender groups allow you to classify unverified senders prior to the 
SMTP conversation and include different types of unverified senders in your various sender groups.

While the connecting host was subject to Host DNS verification in sender groups — prior to the SMTP 
conversation — the domain portion of the envelope sender is DNS verified in mail flow policies, and the 
verification takes place during the SMTP conversation. Messages with malformed envelope senders can 
be ignored. You can add entries to the Sender Verification Exception Table — a list of domains and email 
addresses from which to accept or reject mail despite envelope sender DNS verification settings.

Sender reputation filtering allows you to classify email senders and restrict access to your email 
infrastructure based on sender’s trustworthiness as determined by the Cisco SenderBase Reputation 
Service. 

For more information, see 

.

Using the 

listenerconfig

 command, you can configure a listener to not include the Received: header 

by default to all messages received by the listener.

For more information, see “Advanced Configuration Options” in the “Customizing Listeners” chapter.

You can configure a listener to automatically append a default domain to sender addresses that do not 
contain fully-qualified domain names; these are also known as “bare” addresses (such as “joe” vs. 
“joe@example.com”). 

For more information, see “SMTP Address Parsing Options” in the “Customizing Listeners” chapter.

Outgoing mail is tagged with a special key, and so if that mail is sent back as a bounce, the tag is 
recognized and the mail is delivered. For more information, see “Bounce Verification” in the 
“Configuring Routing and Delivery Features” chapter.

For each listener you configure, you can construct a domain map table which rewrites the envelope 
recipient for each recipient in a message that matches a domain in the domain map table. For example, 
joe@old.com -> joe@new.com

For more information, see “The Domain Map Feature” in the “Configuring Routing and Delivery 
Features” chapter.

For inbound email only, the RAT allows you to specify a list of all local domains for which the appliance 
will accept mail.